Bluetooth: controller: Fix incorrect ext header flag access

Fix Periodic Advertising data population from corrupting
the PDU by populating fields when there is no flags in the
common extended advertising header.

Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>

Author: cvinayak

subsys/bluetooth/controller/ll_sw/ull_adv_sync.c

@@ -801,6 +801,11 @@ static uint8_t adv_sync_hdr_set_clear(struct lll_adv_sync *lll_sync,
 	/* Fill AdvData in tertiary PDU */
 	memmove(ter_dptr, ad_data, ad_len);
 
+	/* Early exit if no flags set */
+	if (!ter_com_hdr->ext_hdr_len) {
+		return 0;
+	}
+
 	/* Fill ACAD in tertiary PDU */
 	ter_dptr_prev -= acad_len_prev;
 	ter_dptr -= acad_len_prev;